The present invention relates to a barrel assembly for an electromagnetic rail gun.
A typical rail gun includes an elongated barrel which has a pair of longitudinally extending parallel conductors or rails disposed symmetrically about its axis. The rails are connected at their rearward, or breech, ends to opposite terminals of a source of direct current. A circuit through the rails may be completed either by a conductor disposed between the rails or by a plasma arc between the rails. This results in the flow of current which generates magnetic flux between the rails. The flux cooperates with the current in the conductor or the plasma arc to accelerate the conductor or plasma forward between the rails. The projectile may include the conductor or may be positioned forward of the conductor or plasma arc and driven forward thereby.
The electromagnetic forces generated during firing of the rail gun tend to drive the rails apart in addition to accelerating the projectile. Also tending to drive the rails apart is gas pressure generated in the barrel during firing. The gas pressure may be particularly high in barrels of rail guns wherein a plasma arc completes the circuit between the rails, due to the vaporization of metal during the initiation of the arc. A more detailed explanation of the initiation of the plasma arc is given in co-pending, commonly assigned U.S. patent application Ser. No. 540,808, which is incorporated herein by reference.
Due to the magnitude of the gas pressure in the barrel during and immediately after firing, it is difficult to prevent gas from entering the interfaces between the insulators and rails. One problem which may result from high pressure gas entering the interfaces is that the forces tending to drive the rails and insulators apart may become excessive due to the increase in the effective surface area on the rails and insulators which is exposed to the high pressure gas. Accordingly, there is a need for means to limit the magnitude of bursting forces which may result from penetration of high-pressure gas into the interfaces.